Allow index lookups on DOLT_DIFF table function.

[nicktobey]

Currently, the DOLT_DIFF table function does not expose any indexes. But it can.

[coffeegoddd]

@nicktobey DOLT

read_tests	from_latency	to_latency	percent_change
covering_index_scan	0.55	0.54	-1.82
groupby_scan	9.73	9.91	1.85
index_join	1.82	1.79	-1.65
index_join_scan	1.32	1.32	0.0
index_scan	22.28	22.69	1.84
oltp_point_select	0.25	0.25	0.0
oltp_read_only	5.0	5.09	1.8
select_random_points	0.5	0.5	0.0
select_random_ranges	0.56	0.56	0.0
table_scan	22.28	22.28	0.0
types_table_scan	47.47	47.47	0.0

write_tests	from_latency	to_latency	percent_change
oltp_delete_insert	6.32	6.32	0.0
oltp_insert	3.07	3.07	0.0
oltp_read_write	11.04	11.04	0.0
oltp_update_index	3.19	3.19	0.0
oltp_update_non_index	3.02	3.02	0.0
oltp_write_only	5.99	5.99	0.0
types_delete_insert	6.67	6.67	0.0

[coffeegoddd]

@nicktobey DOLT

test_name	from_latency_p95	to_latency_p95	percent_change
tpcc-scale-factor-1	53.85	54.83	1.82

test_name	from_server_name	from_server_version	from_tps	to_server_name	to_server_version	to_tps	percent_change
tpcc-scale-factor-1	dolt	e7c19b9	45.1	dolt	7e3f1c9	43.86	-2.75

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
c1d997d	ok	5937471

version	total_tests
c1d997d	5937471

correctness_percentage
100.0

[coffeegoddd]

@coffeegoddd DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
175e274	ok	5937471

version	total_tests
175e274	5937471

correctness_percentage
100.0

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
8233d80	ok	5937471

version	total_tests
8233d80	5937471

correctness_percentage
100.0

[coffeegoddd]

@coffeegoddd DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
85eb379	ok	5937471

version	total_tests
85eb379	5937471

correctness_percentage
100.0

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
7cfd19d	ok	5937471

version	total_tests
7cfd19d	5937471

correctness_percentage
100.0

[coffeegoddd]

@coffeegoddd DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
0808eb3	ok	5937471

version	total_tests
0808eb3	5937471

correctness_percentage
100.0

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
1d82310	ok	5937471

version	total_tests
1d82310	5937471

correctness_percentage
100.0

[coffeegoddd]

@coffeegoddd DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
35cd39b	ok	5937471

version	total_tests
35cd39b	5937471

correctness_percentage
100.0

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
259c725	ok	5937471

version	total_tests
259c725	5937471

correctness_percentage
100.0

[coffeegoddd]

@coffeegoddd DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
4452093	ok	5937471

version	total_tests
4452093	5937471

correctness_percentage
100.0

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
c7d6319	ok	5937471

version	total_tests
c7d6319	5937471

correctness_percentage
100.0

[coffeegoddd]

@coffeegoddd DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
d35223d	ok	5937471

version	total_tests
d35223d	5937471

correctness_percentage
100.0

[zachmu]

LGTM!

[coffeegoddd]

@nicktobey DOLT

comparing_percentages
100.000000 to 100.000000

version	result	total
7e3f1c9	ok	5937471

version	total_tests
7e3f1c9	5937471

correctness_percentage
100.0